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bitops.h

Go to the documentation of this file.

/* $Id: bitops.h 27933 2007-03-08 10:15:20Z adam $ */
/*****************************************************************************/
/*
 * Copyright (C) 2000-2002
 * Dresden University of Technology, Operating Systems Research Group
 *
 * This file contains free software, you can redistribute it and/or modify
 * it under the terms of the GNU General Public License, Version 2 as
 * published by the Free Software Foundation (see the file COPYING).
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * For different licensing schemes please contact
 * <contact@os.inf.tu-dresden.de>.
 */
/*****************************************************************************/
#ifndef __L4UTIL__INCLUDE__BITOPS_H__
#define __L4UTIL__INCLUDE__BITOPS_H__

/* L4 includes */
#include <l4/sys/l4int.h>
#include <l4/sys/compiler.h>

#define l4util_test_and_clear_bit(b, dest)      l4util_btr(b, dest)
#define l4util_test_and_set_bit(b, dest)        l4util_bts(b, dest)
#define l4util_test_and_change_bit(b, dest)     l4util_btc(b, dest)
#define l4util_log2(word)                       l4util_bsr(word)

/*****************************************************************************
 *** Prototypes
 *****************************************************************************/

EXTERN_C_BEGIN

L4_INLINE void
l4util_set_bit(int b, volatile l4_umword_t * dest);

L4_INLINE void
l4util_set_bit32(int b, volatile l4_uint32_t * dest);

#if L4_MWORD_BITS >= 64
L4_INLINE void
l4util_set_bit64(int b, volatile l4_uint64_t * dest);
#endif

L4_INLINE void
l4util_clear_bit(int b, volatile l4_umword_t * dest);

L4_INLINE void
l4util_clear_bit32(int b, volatile l4_uint32_t * dest);

#if L4_MWORD_BITS >= 64
L4_INLINE void
l4util_clear_bit64(int b, volatile l4_uint64_t * dest);
#endif

L4_INLINE void
l4util_complement_bit(int b, volatile l4_umword_t * dest);

L4_INLINE int
l4util_test_bit(int b, const volatile l4_umword_t * dest);

L4_INLINE int
l4util_test_bit32(int b, const volatile l4_uint32_t * dest);

#if L4_MWORD_BITS >= 64
L4_INLINE int
l4util_test_bit64(int b, const volatile l4_uint64_t * dest);
#endif

L4_INLINE int
l4util_bts(int b, volatile l4_umword_t * dest);

L4_INLINE int
l4util_btr(int b, volatile l4_umword_t * dest);

L4_INLINE int
l4util_btc(int b, volatile l4_umword_t * dest);

L4_INLINE int
l4util_bsr(l4_umword_t word);

L4_INLINE int
l4util_bsf(l4_umword_t word);

L4_INLINE int
l4util_find_first_set_bit(const void * dest, l4_size_t size);

L4_INLINE int
l4util_find_first_zero_bit(const void * dest, l4_size_t size);


EXTERN_C_END

/*****************************************************************************
 *** Implementation of specific version
 *****************************************************************************/

#include <l4/util/bitops_arch.h>

/*****************************************************************************
 *** Generic implementations
 *****************************************************************************/

#ifndef __L4UTIL_BITOPS_HAVE_ARCH_SET_BIT
#include <l4/util/atomic.h>
L4_INLINE void
l4util_set_bit(int b, volatile l4_umword_t * dest)
{
  l4_umword_t oldval, newval;

  dest += b / (sizeof(*dest) * 8); /* advance dest to the proper element */
  b    &= sizeof(*dest) * 8 - 1;   /* modulo; cut off all upper bits */

  do
    {
      oldval = *dest;
      newval = oldval | (1 << b);
    }
  while (!l4util_cmpxchg(dest, oldval, newval));
}
#endif

#ifndef __L4UTIL_BITOPS_HAVE_ARCH_CLEAR_BIT
#include <l4/util/atomic.h>
L4_INLINE void
l4util_clear_bit(int b, volatile l4_umword_t * dest)
{
  l4_umword_t oldval, newval;

  dest += b / (sizeof(*dest) * 8);
  b    &= sizeof(*dest) * 8 - 1;

  do
    {
      oldval = *dest;
      newval = oldval & ~(1 << b);
    }
  while (!l4util_cmpxchg(dest, oldval, newval));
}
#endif

#ifndef __L4UTIL_BITOPS_HAVE_ARCH_TEST_BIT
L4_INLINE int
l4util_test_bit(int b, const volatile l4_umword_t * dest)
{
  dest += b / (sizeof(*dest) * 8);
  b    &= sizeof(*dest) * 8 - 1;

  return (*dest >> b) & 1;
}
#endif

#ifndef __L4UTIL_BITOPS_HAVE_ARCH_TEST_BIT32
L4_INLINE int
l4util_test_bit32(int b, const volatile l4_uint32_t * dest)
{
  dest += b / (sizeof(*dest) * 8);
  b    &= sizeof(*dest) * 8 - 1;

  return (*dest >> b) & 1;
}
#endif

#ifndef __L4UTIL_BITOPS_HAVE_ARCH_BIT_TEST_AND_SET
#include <l4/util/atomic.h>
L4_INLINE int
l4util_bts(int b, volatile l4_umword_t * dest)
{
  l4_umword_t oldval, newval;

  dest += b / (sizeof(*dest) * 8);
  b    &= sizeof(*dest) * 8 - 1;

  do
    {
      oldval = *dest;
      newval = oldval | (1 << b);
    }
  while (!l4util_cmpxchg(dest, oldval, newval));

  /* Return old bit */
  return (oldval >> b) & 1;
}
#endif

#ifndef __L4UTIL_BITOPS_HAVE_ARCH_BIT_TEST_AND_RESET
#include <l4/util/atomic.h>
L4_INLINE int
l4util_btr(int b, volatile l4_umword_t * dest)
{
  l4_umword_t oldval, newval;

  dest += b / (sizeof(*dest) * 8);
  b    &= sizeof(*dest) * 8 - 1;

  do
    {
      oldval = *dest;
      newval = oldval & ~(1 << b);
    }
  while (!l4util_cmpxchg(dest, oldval, newval));

  /* Return old bit */
  return (oldval >> b) & 1;
}
#endif

#ifndef __L4UTIL_BITOPS_HAVE_ARCH_BIT_SCAN_REVERSE
L4_INLINE int
l4util_bsr(l4_umword_t word)
{
  int i;

  if (!word)
    return -1;

  for (i = 8 * sizeof(word) - 1; i >= 0; i--)
    if ((1 << i) & word)
      return i;

  return -1;
}
#endif

#ifndef __L4UTIL_BITOPS_HAVE_ARCH_BIT_SCAN_FORWARD
L4_INLINE int
l4util_bsf(l4_umword_t word)
{
  unsigned int i;

  if (!word)
    return -1;

  for (i = 0; i < sizeof(word) * 8; i++)
    if ((1 << i) & word)
      return i;

  return -1;
}
#endif

#ifndef __L4UTIL_BITOPS_HAVE_ARCH_FIND_FIRST_ZERO_BIT
L4_INLINE int
l4util_find_first_zero_bit(const void * dest, l4_size_t size)
{
  l4_size_t i, j;
  unsigned long *v = (unsigned long*)dest;

  if (!size)
    return 0;

  size = (size + 31) & ~0x1f; /* Grmbl: adapt to x86 implementation... */

  for (i = j = 0; i < size; i++, j++)
    {
      if (j >= sizeof(*v) * 8)
        {
          j = 0;
          v++;
        }
      if (!((1 << j) & *v))
        return i;
    }
  return size + 1;
}
#endif

#ifndef __L4UTIL_BITOPS_HAVE_ARCH_COMPLEMENT_BIT
L4_INLINE void
l4util_complement_bit(int b, volatile l4_umword_t * dest)
{
  dest += b / (sizeof(*dest) * 8);
  b    &= sizeof(*dest) * 8 - 1;

  *dest ^= 1UL << b;
}
#endif

#endif /* ! __L4UTIL__INCLUDE__BITOPS_H__ */

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